: december? ( timestamp -- ? ) month>> 12 = ;
: weekend? ( timestamp -- ? ) day-of-week { 0 6 } member? ;
-: weekday? ( timestamp -- ? ) day-of-week weekend? not ;
+: weekday? ( timestamp -- ? ) weekend? not ;
: same-or-next-business-day ( timestamp -- timestamp' )
dup day-of-week {